The homemade bombs, also called improvised explosive devices or IEDs, are responsible for between 70 percent and 80 percent of the casualties among U.S. and coalition forces in Afghanistan and have become a weapon of "strategic influence," said Lt. Gen. Thomas Metz, in Washington.

The attacks yesterday followed one of the deadliest days for the U.S. military operation in Afghanistan - grim milestones likely to fuel the debate in the United States over whether the conflict is worth the sacrifice.

Obama has nearly finished gathering information on whether to send tens of thousands more American forces to quell the deepening insurgency, White House press secretary Robert Gibbs said. A meeting Friday with the Joint Chiefs of Staff will be among the last events in the decision-making process, Gibbs said.

Both attacks yesterday took place in the southern province of Kandahar, said Capt. Adam Weece, a spokesman for American forces in the south. The region bordering the Pakistan frontier has long been an insurgent stronghold and was the birthplace of the Taliban in the 1990s.

Meanwhile, the Associated Press reported yesterday that there already are more than 100,000 international troops in Afghanistan working with 200,000 Afghan security forces and police. It adds up to a 12-1 numerical advantage over Taliban rebels, but it hasn't led to anything close to victory.

Now, the top U.S. and NATO commander in Afghanistan is asking for tens of thousands more troops to stem the escalating insurgency, raising the question of how many more troops it would take to succeed.

The commander, Gen. Stanley McChrystal, says the extra forces are needed to implement a strategy that focuses on protecting civilians and depriving the militants of popular support in a country where tribal militias may be Taliban today and farmers tomorrow.

"The U.S. and its allies already have ample numbers and firepower to annihilate the Taliban, if only the Taliban would cooperate by standing still and allowing us to bomb them to smithereens," said Andrew Bacevich, a professor of international relations and history at Boston University, and who was a platoon leader in Vietnam."

Adding to the controversy and the pressure to do something, a Marine who fought in Iraq and became a diplomat in a Taliban stronghold in Afghanistan has resigned in a high-profile protest of the Afghan war.

Foreign service officer Matthew Hoh is the first U.S. official known to have quit in protest to the war, according to the Washington Post, which yesterday reported Hoh's resignation.

Hoh said he stepped down only six months into the job because he believed the war is fueling the insurgency. The State Department said it respected his views but did not agree with them.

"I have lost understanding of and confidence in the strategic purposes of the United States' presence in Afghanistan," Hoh wrote in his Sept. 10 resignation letter.

"I have doubts and reservations about our current strategy and planned future strategy, but my resignation is based not upon how we are pursuing this war, but why and to what end."

Hoh's resignation took effect on Sept. 28, according to State Department spokesman Ian Kelly, who said the government appreciated his Hoh's service in Iraq and as a political officer in Zabul, Afghanistan.

"We take his point of view very seriously, but we continue to believe that we're on track to achieving the goal that the president has set before us," Kelly told reporters.

Kelly noted that senior U.S. officials in both Afghanistan and Washington had met with Hoh and "heard him out." "We respect his right to dissent."

However, Kelly pointed out that Hoh was a temporary hire whose tour was to end in March after the completion of a limited one-year assignment and that his resignation was not comparable to those of career diplomats who stepped down to protest U.S. military actions in Bosnia and Iraq.

And finally, the Drug Enforcement Administration yesterday identified the three agents killed Monday in a helicopter crash in Afghanistan, the agency's first fatalities in its counter-narcotics operations in that country.

They were Special Agent Forrest Leamon, 37, of Woodbridge, Va., Special Agent Chad Michael, 30, of Quantico, Va., and Special Agent Michael Weston, 37, of Washington, D.C. The men were assigned to the agency's fight against Afghanistan's opium trade, which often funds insurgent activity.